Problem: Nadia had to read papers 42 through 62 for homework tonight. If Nadia read all of the papers she was assigned, how many papers did she read?
Solution: Instead of counting papers 42 through 62, we can subtract 41 from each number so we instead consider papers 1 through 21. We see that Nadia read 21 papers. Notice that she read 21 and not 20 papers.